by Cass Sunstein

In response to Jacob Levy's generous invitation: The likely answer is that Congress can refuse to appropriate funds for the "surge," and can, in that sense, forbid the president from doing what he seeks to do. As a general rule, Congress has the power to authorize appropriations as it sees fit, and if it forbids use of funds for an increase in the use of military personnel in Iraq, it is constitutionally secure. (I am not discussing the policy issues here in any way.) But there are some complexities here. The best counterargument would a) insist that Congress' appropriations power is limited by other constitutional provisions and b) invoke the Commander-in-Chief Clause. It is true that the president is permitted to decide how to wage war, once Congress has authorized war. Congress could not enact a law saying that military troops in Iraq will be used in one way, or in one area of Iraq, rather than another; military strategy is for the president alone. It is a nice question whether Congress could use its appropriations authority to interfere with the president's strategic judgments as commander-in-chief. (Imagine an appropriations bill forbidding any use of federal funds to support specified movements of troops on a field of battle--or an appropriations bill saying that such funds can be used only to support troops movements in one direction, and a certain number of yards, in a given week.) But it is pretty clear that if Congress wants to support a war to X extent, with X commitment of funds, the president lacks the authority to insist that he needs a funding commitment greater than X. The president might argue that so long as war is authorized, he alone can decide on its extent, within the domain of the authorization. If he wants to move troops from outside of Iraq into Iraq, he can do exactly that. On this view, he is entitled to expend funds and move personnel as he deems fit, and Congress' only options are a) to repeal or end the authorization altogether or b) to defund the war entirely (as John Yoo, a very strong defender of executive power, seems to believe that Congress can constitutionally do). But if Congress can defund a war entirely, and deprive the president of authority in that way, it can almost surely limit the level of funding devoted to the war effort. The upshot is that because it has power over appropriations, Congress can probably refuse to permit a surge, or military build-up, at least through refusing to allow taxpayer money to be used for that purpose. (A more general point is that constitutional questions involving the president's authority are not all of a piece; the analysis of the appropriations issue is altogether different, for example, from the analysis of foreign surveillance, or of presidential signing statements.)